These are Cicada Killer wasps. They do not pose a risk to the tree (or any other plants) at all; they merely dig burrows in the soil in which to lay eggs and stash cicadas to feed their young. The burrows do not kill roots and, if anything, may benefit the tree because they help improve drainage and oxygenation of the root zone. Spruces struggle in our mid-Atlantic climate, especially with high heat and drought, so other issues unrelated to the wasps are causing decline if borers have been damaging its trunk. A certified arborist might be able to help with spruce diagnosis. Wood-boring insects (often beetles) usually target trees under stress rather than healthy trees.

Despite the intimidating size of these native wasps, they do not take an interest in people and should not sting. (The only exception might be if a female is accidentally stepped-on barefoot or swatted repeatedly.) Male wasps cannot sting, and will sit on nearby perches to watch for females and rival males to chase off. He might approach a person to investigate what they are, but will not harm people. The females are busy drinking nectar from flowers (or sap flow from trees) for a sugar source, and are otherwise occupied finding and grabbing cicadas in the treetops, hauling them back to the burrow by themselves. Cicada Killer wasps can nest in clusters because soil conditions in that area appeal to them, but each female wasp works by herself; they do not share a nest, or defend a shared nest, the way that yellowjackets and hornets do. The adult wasps will finish their activity in a few more weeks, and then will be gone.

Miri

Adult wasps can only feed on liquid food sources, and that is primarily sugars in sap, ripe fruits (like peaches), flower nectar, and honeydew (a sugar-water substance certain insects excrete). They cannot eat solid food themselves, but the insects they catch (in this case, only cicadas) are brought back to the nest (burrow) to serve as food for their young, which do eat "meat." Some wasps are more generalists, and can hunt and catch caterpillars, flies, and various other insects for their young. Others are highly specialized, like Cicada Killers, and only hunt one type (or very few types) of insect or spider prey.

Adult Cicada Killer wasps do not survive long enough to overwinter. By autumn, this generation of adults will have died, and only their young, tucked into and insulated by their soil burrows, survive and will mature and hatch into a new generation of adults next summer. What you saw last year was probably a different wasp (or several different wasp or bee species).

Miri